Control of lung function

Question 1

Where are the 4 main respiratory nuclei and what are they?

Answer 1

Medulla Oblongata

Dorsal Respiratory group
Ventral respiratory group
Apneustic centre
Pneumotaxic centre

Question 2

What is the dorsal respiratory group responsible for?

Answer 2

Inspiratory centre
Main ‘controller’ of inspiration
Set the ‘rate’

Question 3

What is the ventral respiratory group responsible for?

Answer 3

Expiratory centre
Inactive during quiet breathing
Inhibit apneustic centre

Question 3

What is the apneustic centre responsible for?

Answer 3

Stimulates activity in DRG
Inhibited by pulmonary afferents

Question 4

What is the pneumotaxic centre responsible for?

Answer 4

The ‘inspiratory off switch’
Regulates depth & frequency

Question 5

What groups are responsible for inspiration and expiration?

Answer 5

Inspiration: DRG, Apneustic centre

Expiration: VRG, Pneumotaxic centre

Question 6

How do the different respiratory nuclei control eachother?

Answer 6

Question 7

What centres are active at the start and end of inspiration?

Answer 7

Start: Apneustic centre

End: Pneumotaxic centre

Question 8

What kind of pattern is shown in the respiratory pacemaker?

Answer 8

A ‘ramp potential’ pattern

Question 9

How is the diaphragm innervated?

Answer 9

Phrenic nerve

Question 10

How are the intercostal muscles innervated?

Answer 10

Intercostal nerves from T1-T11

Question 10

How are the lungs themselves sympathetically/parasympathetically innervated?

Answer 10

Symp: From sympathetic trunk ganglia

Parasymp: Jugular ganglion in pons

-Both fuse at pulmonary plexuses

Question 11

What kind of vessel walls do you have in normal circulation?

Answer 11

Question 12

What kind of vessel walls do you have along the blood brain barrier?

Answer 12

Question 13

Describe the transfer of molecules through the blood brain barrier

Answer 13

CO2(due to high lipid solubility) passes from capillary to CSF

CO2 in CSF turns in carbonic acid, which dissociates

H+ from acid passes into the medulla into projections from the DRG

Question 14

Where are irritant receptors found and what is their function?

Answer 14

Trachea

Afferent receptors embedded within and beneath airway epithelium
Leads to cough: which involves forceful expiration against a closed glottis with sudden glottal opening & high velocity expulsion of air

Question 15

Where are stretch receptors found in the CP circuit and what is their function?

Answer 15

Lobar bronchi

Excessive inflation of lungs activates pulmonary stretch receptors
Afferent signals to respiratory centres inhibit DRG and apneustic centre and stimulate pneumotaxic VRG
Inspiration inhibited & expiration stimulated

Question 16

Where are J-receptors found and what is their function?

Answer 16

Alveolar sacs

Sensitive to oedema and pulmonary capillary engorgement
Increases breathing frequency

Question 17

How does pH affect proteins?

Answer 17

By altering their 3D stucture

Question 18

What occurs to chloride ions as carbonic acid dissociates in blood cells?

Answer 18

Cl- enters the cell to balance the charge equilibrium

Question 19

pH equation

Answer 19

pH = -log(10)[H+}

Question 20

def Alkalaemia

Answer 20

Higher than normal blood pH

Question 21

def Acidaemia

Answer 21

Lower than normal blood pH

Question 22

def Alkalosis

Answer 22

Conditions generating a high pH

Question 23

def Acidosis

Answer 23

Conditions generating a low pH

Question 24

How does the speed of pH buffering differ in the kidneys/lungs?

Answer 24

Changes in ventilation issue a rapid response

Changes in renal secretions issue a slow response

Question 25

Where are the peripheral chemoreceptors and what what nerves are they innervated by?

Answer 25

Aortic: X

Carotic: IX

Question 26

What 2 factors elicit an emotional response which affects the respiratory control center?

Answer 26

Higher brain centres
Special senses

Question 27

How are the ventilation groups in medulla innervated by exercise?

Answer 27

Efferents from primary motor cortex to gross skeletal musculature partly innervate medulla

Proprioceptive afferents from muscle spindles & golgi tendon organs innervate medulla on way to brain